Efficient Pt-FeO: X/TiO2@SBA-15 catalysts for selective hydrogenation of cinnamaldehyde to cinnamyl alcohol

Article abstract of DOI:10.1039/c7cy02008b

TiO₂ was coated onto mesoporous silica SBA-15 by hydrolysis of tetrabutyl titanate to prepare 15 wt% TiO₂@SBA-15 composites (15TS). The 15TS composites retain the mesostructure of the SBA-15 host, and TiO₂ was highly dispersed and uniformly coated. 5 wt% Pt nanoparticles supported on 15TS were employed for liquid-phase selective hydrogenation of cinnamaldehyde (CAL) to cinnamyl alcohol (COL). Compared with the Pt catalyst supported on pristine SBA-15, the Pt/15TS catalyst afforded higher activity and selectivity to COL. Furthermore, the modification of the Pt/15TS catalyst by FeO_x can greatly improve the activity and selectivity to COL. As a result, the Pt-FeO_x/15TS catalyst displayed excellent selectivity to COL (around 84.5%) at nearly complete CAL conversion. Of particular note is that further calcination of the Pt-FeO_x/15TS catalyst precursor in air at 773 K before reduction would greatly enhance the catalytic performance. Consequently, the TOF reached 3.06 s^-1 with a selectivity to COL of 86.4% over the Pt-FeO_x/15TS-773 catalyst. Moreover, the Pt-FeO_x/15TS-773 catalyst can also be reused about eight times without distinct loss in activity or selectivity. Based on characterization by XPS and H₂-TPR, the important promotion effect of FeO_x and strong metal-support interaction played key roles in preferential adsorption and activation of CO bonds in CAL.

Full text of DOI:10.1039/c7cy02008b

Catalysis
Science &
Technology
View Article Online
View Journal
PAPER
Efficient Pt–FeO /TiO @SBA-15 catalysts for
x
2
selective hydrogenation of cinnamaldehyde to
cinnamyl alcohol
Cite this: DOI: 10.1039/c7cy02008b
Yujie Xue, Ruihua Yao, Junrui Li, Guimei Wang, Peng Wu
and Xiaohong Li
*
TiO
TiO
TiO
2
2
2
was coated onto mesoporous silica SBA-15 by hydrolysis of tetrabutyl titanate to prepare 15 wt%
@SBA-15 composites (15TS). The 15TS composites retain the mesostructure of the SBA-15 host, and
was highly dispersed and uniformly coated. 5 wt% Pt nanoparticles supported on 15TS were employed
for liquid-phase selective hydrogenation of cinnamaldehyde (CAL) to cinnamyl alcohol (COL). Compared
with the Pt catalyst supported on pristine SBA-15, the Pt/15TS catalyst afforded higher activity and selectiv-
ity to COL. Furthermore, the modification of the Pt/15TS catalyst by FeO
and selectivity to COL. As a result, the Pt–FeO /15TS catalyst displayed excellent selectivity to COL (around
4.5%) at nearly complete CAL conversion. Of particular note is that further calcination of the Pt–FeO
5TS catalyst precursor in air at 773 K before reduction would greatly enhance the catalytic performance.
x
can greatly improve the activity
x
8
x
/
1
−1
Received 30th September 2017,
Accepted 13th November 2017
x
Consequently, the TOF reached 3.06 s with a selectivity to COL of 86.4% over the Pt–FeO /15TS-773 cat-
alyst. Moreover, the Pt–FeO
activity or selectivity. Based on characterization by XPS and H
FeO and strong metal–support interaction played key roles in preferential adsorption and activation of
CO bonds in CAL.
x
/15TS-773 catalyst can also be reused about eight times without distinct loss in
2
-TPR, the important promotion effect of
DOI: 10.1039/c7cy02008b
x
rsc.li/catalysis
Noble metal-based catalysts have been widely used for the
1
. Introduction
8
,15–21
hydrogenation of CAL.
high activities but rather poor selectivities towards COL.
Pd and Rh generally displayed
2
2
Chemoselective hydrogenation of α,β-unsaturated aldehydes
at carbonyl (CO) groups to produce α,β-unsaturated alco-
hols is an important reaction. As a particularly important rep-
resentative of α,β-unsaturated aldehydes, selective hydrogena-
tion of cinnamaldehyde (CAL) can produce cinnamyl alcohol
Comparatively, Pt and Ru are commonly used metals
exhibiting relatively higher catalytic performance to obtain
1
4,19–21,23
the desired unsaturated alcohol.
In addition, the
promotion of Pt catalysts by transition metals like Fe, Co, Sn,
Zn or Cu can greatly improve the selectivity toward the unsat-
(COL), which is generally considered as one of the most chal-
2
4–29
lenging and valuable intermediates and then largely used in
several chemical industries such as perfumes, flavors, and
pharmaceuticals.
bonds bear a higher bond energy than CC bonds (715 kJ
mol versus 615 kJ mol , respectively), the hydrogenation of
CC bonds is more thermodynamically favorable. Therefore,
the development of catalysts for the selective hydrogenation
of CAL to COL remains a difficult challenge. As is well
urated alcohol.
2
For instance, SiO -supported Pt–Fe cata-
lysts were prepared to study their structure, chemisorptive,
and catalytic properties promoting the selective hydrogena-
tion of CO bonds and the formation of α,β-unsaturated
1
–6
However, owing to the fact that CO
−
1
−1
7
25
alcohols. In addition, Pt–Zn and Pt–Fe catalysts supported
8
on mesoporous carbon materials were applied for CAL hydro-
genation, both of which improved the activity and induced a
9
28
remarkable increase in selectivity to COL. There are other
known, chemoselectivity is affected by considerable parame-
ters, so that the rational design of active and selective cata-
lysts for selective hydrogenation of CAL is not an easy task.
Thus, people have made many efforts in selective hydrogena-
examples, such as Pt–Fe/CNTs (carbon nanotubes) and Pt–
Co/CNTs which displayed high activity and selectivity to COL
2
7
as well. Besides, a SnO -isolated Pt Sn alloy on reduced
2
3
graphene oxide served as an efficient catalyst for selective hy-
drogenation of CO in unsaturated aldehydes and furnished
up to 92.5% selectivity to COL at a CAL conversion of 93.9%
1
0–14
tion of CAL to COL during the past decades.
2
9
under mild conditions.
Shanghai Key Laboratory of Green Chemistry and Chemical Processes, School of
Chemistry and Molecular Engineering, East China Normal University, 3663 North
Zhongshan Rd., Shanghai 200062, China. E-mail: xhli@chem.ecnu.edu.cn;
Fax: +86 21 62238590; Tel: +86 21 62238590
Moreover, the electronic and stereo-hindrance effects
would affect the adsorption mode of CAL on the catalyst sur-
face; however, the key factors that control the activity and
This journal is © The Royal Society of Chemistry 2017
Catal. Sci. Technol.

View Article Online
Paper
Catalysis Science & Technology
2
4,30
selectivity in the hydrogenation of CAL are still unclear.
nation of CAL (Scheme 1). To further enhance the catalytic
Because the interaction between the support and metal can
modulate the surface electronic properties of the active
metal, it would be a feasible way to adopt appropriate mate-
rials to load Pt nanoparticles for the liquid-phase hydrogena-
tion of CAL. Since Tauster and Fung found that a strong
metal–support interaction existed between noble metals and
behaviors, FeO with an optimal amount was also doped to
x
the Pt/TiO
2
@SBA-15 catalyst for the tested reaction. To our
delight, the FeO -doped Pt/TiO @SBA-15 catalyst afforded
x
2
high activity and selectivity to COL and could be easily
recycled several times without obvious loss in activity or
selectivity to COL.
3
1
TiO2 in the late 1970s, application of reducible supports
such as TiO (ref. 32–34) and CeO (ref. 35) aroused inten-
sive interest. For instance, Pt/TiO and Ni/TiO catalysts were
2
2
2
2
2
. Experimental
3
3,36
investigated in the hydrogenation of aldehydes.
In addi-
2.1. Catalyst preparation
tion, 2 wt% Ru/TiO and 4.7 wt% Sn/TiO catalysts were also
2
2
3
7
45
studied for the hydrogenation of methyl oleate. It was
proved that the strong interaction between metal and TiO2
suppressed the migration and aggregation of metal particles
SBA-15 was synthesized according to the literature. 15 wt%
TiO @SBA-15 (15TS) composites were prepared by hydrolysis
2
of tetrabutyl titanate (TBT) onto SBA-15 via a sol–gel
3
0,33,36–39
44
on the TiO2 surface.
Thus, the strong interaction
method. A typical procedure for the preparation of 15TS
would influence the surface electronic properties of noble
metals and likely in turn bring considerable changes in their
was as follows: SBA-15 was sonicated in isopropanol for 2 h
(the mass ratio of SBA-15 to isopropanol is 1 : 15) and then,
the required amount of TBT was added dropwise with stir-
ring for 1 h. Then, water was slowly added and the stirring
was maintained for an extra 2 h to complete the hydrolysis of
TBT. The as-prepared materials were recovered by filtration,
rinsed with deionized water and ethanol, dried at 353 K over-
night, and finally calcined at 623 K for 2 h.
activity in catalytic reactions. Nevertheless, TiO has serious
2
disadvantages when used as a catalyst support itself. First,
2
TiO usually has small specific surface area, so that the ad-
sorption and concentration of reactants around the active
4
0
centers are limited. Second, the required liquid–solid sepa-
ration is difficult due to the formation of milky dispersion
4
1
once the TiO powder catalyst is mixed in water. Therefore,
The 5 wt% Pt/15TS catalyst was prepared via an impregna-
2
we attempt to introduce TiO
2
onto the SBA-15 surface to pre-
2
tion method using an ethanolic solution of H PtCl6. The sus-
pare TiO @SBA-15 composites.
2
pension was stirred for 4–6 h at room temperature, then
evaporated to remove the excess solvent, followed by drying
overnight at 353 K, and finally reduced in an aqueous solu-
tion of sodium formate at 363 K for 2 h. For comparison, 5
wt% Pt/TiO2 and 5 wt% Pt/SBA-15 catalysts were also pre-
pared using the same method.
It is well known that SBA-15 has high specific surface
area, large pore volume and adjustable pore size, which
make it an ideal support for the preparation of highly dis-
3
9,42,43
persed heterogeneous catalysts.
The introduction of
@SBA-15
TiO onto the SBA-15 surface can produce TiO
2
2
composites, which not only take advantage of mesoporous
materials with large specific surface area and pore volume,
x
The Pt–FeO /15TS catalyst containing 5 wt% Pt and 0.36
wt% Fe (where the Fe/Pt molar ratio is 0.25) was prepared
using the similar method to that for the Pt/15TS catalyst, ex-
but also exhibit properties not found in bulk TiO
our previous studies, it has been proved that TiO
composite-supported Pt catalysts behaved much better than
TiO or SBA-15 supported ones for liquid-phase hydrogena-
tion of benzaldehyde. It is anticipated that the TiO
5 composite-supported Pt catalysts can still show striking
2
alone. In
2
@SBA-15
2 6 3
cept that the ethanolic solution of H PtCl and FeCl were
added together to impregnate 15TS composites. Additionally,
some catalyst precursors before reduction were also calcined
in air at 473 K or 773 K for 2 h and the resultant catalysts
2
4
4
2
@SBA-
1
were denoted as Pt–FeO /15TS-T, where T represents the cal-
x
catalytic performance in the liquid-phase selective hydroge-
cination temperature in Kelvin for the catalyst precursor.
Scheme 1 Selective hydrogenation of CAL.
Catal. Sci. Technol.
This journal is © The Royal Society of Chemistry 2017

View Article Online
Catalysis Science & Technology
Paper
2
.2. Characterization
and CAL without further exposure to air, which was subse-
quently transferred to a 100 mL autoclave. The hydrogena-
tion reaction began with stirring (1200 rpm) at 363 K after
hydrogen (99.999% purity) was introduced into the auto-
clave. The reaction was stopped after an appropriate time,
and then the products were analyzed using a GC-FID (GC-
Powder X-ray diffraction (XRD) patterns of the samples were
collected on a Bruker D8 ADVANCE instrument using Cu Kα
radiation (λ = 1.54178 Å) as the X-ray source. The N -
2
physisorption isotherms of the samples were measured at 77
K on a Quantachrome Autosorb-3B system after the samples
were evacuated at 573 K for 4 h. The Brunauer–Emmett–
Teller (BET) specific surface area was calculated using ad-
sorption data in the relative pressure range from 0.05 to 0.35.
The pore size distribution curves were calculated from analy-
sis of the adsorption branch of the isotherm using the
Barrett–Joyner–Halenda (BJH) algorithm. The morphology of
2
014, Shimadzu Co.) equipped with a flame ionization detec-
tor (FID) and capillary column (DM-WAX, 30 m × 0.25 mm ×
.25 μm). The response factor of each component was calcu-
0
lated using the standard sample and used to calculate the
conversion and selectivity.
the samples was measured by scanning electron microscopy 3. Results and discussion
(
SEM) using a Hitachi S4800 electron microscope with an ac-
3
.1. Characterization of the catalysts
The Pt/15TS and Pt–FeO /15TS catalysts were firstly character-
ized by low-angle powder XRD. As displayed in Fig. 1, the
5TS composites displayed the typical (100), (110) and (200)
celerating voltage of 20 kV. The transmission electron micros-
copy (TEM) images were taken on an FEI Tecnai G2-TF30
microscope at an accelerating voltage of 300 kV. The amount
of Pt atoms leached into the filtrate after recycling reaction
was determined by inductively coupled plasma-atomic emis-
sion spectroscopy (ICP-AES) using a Thermo Elemental IRIS
Intrepid II XSP.
The surface electronic properties of Pt were examined
using X-ray photoelectron spectroscopy (XPS) with a Thermo
Fisher Scientific ESCALAB 250Xi spectrometer with Al Kα ra-
diation (1486.6 eV) as the incident beam with a monochro-
mator. The samples were pre-treated in situ in flowing hydro-
gen at 673 K for 2 h in a reactor attachment of the XPS
spectrometer. For comparison, the as-calcined samples with-
out reduction were also probed by XPS. The binding energy
x
1
diffraction peaks in the region of 2θ = 0.5–2°, which are char-
acteristic of the P6mm hexagonal structure of the SBA-15
host. All the Pt-based catalysts possessed the typical meso-
porous structure similar to that of the SBA-15 host, demon-
strating that the loading of TiO and Pt nanoparticles did not
destroy the ordered structure of the SBA-15 host. The meso-
porous structure of the Pt-based catalysts was further con-
firmed by N sorption (Fig. 2) and SEM (Fig. 3). Both the Pt/
1
therms with hysteresis loops, suggesting that they retained
the mesoporous structure. For clarity, Table 1 lists the de-
tailed physicochemical parameters of the related samples. On
the whole, the pore volume and the BET specific surface area
2
2
x
5TS and Pt–FeO /15TS catalysts showed typical type IV iso-
(BE) was calibrated using C–C binding energy at 284.4 eV in
order to compare the BEs with the data from the literature.
The spectra shown in the figures have been corrected by Shir-
ley background subtraction. Spectral fitting and peak integra-
tion was performed using XPSPEAK software. During
deconvolution of XPS spectra, the FWHM (full width at half
of the Pt/15TS and Pt–FeO /15TS catalysts decreased a little
compared with those of the SBA-15 host, indicating that the
introduced TiO
certain mesoporous channel. As a result, the Pt/15TS catalyst
x
2
and deposited Pt nanoparticles occupied a
2
−1
0
2+
has a BET specific surface area of 345 m g . When FeOx
maxima) were set at 1.8 and 2.5 eV for Pt and Pt species,
respectively. The Lorentzian–Gaussian ratio was set to 20%.
Temperature-programmed reduction with hydrogen (H
TPR) was conducted to investigate the interaction between Pt
and the support or FeO with a Micromeritics AutoChem II
chemisorption analyzer. Prior to H -TPR experiments, 250 mg
2
-
x
2
of the catalyst was pre-treated at 573 K in flowing Ar for 1 h
and then cooled to room temperature in flowing Ar
−
1
(
99.999%, 50 mL min ). After that, the sample was heated
from room temperature to 1193 K with a heating rate of 10 K
−
1
−1
min under a mixture of 10% H
of H consumption was monitored by a gas chromatograph
GC) with a thermal conductivity detector (TCD).
2
–Ar (50 mL min ). The rate
2
(
2
.3. Catalytic test
A certain amount of the catalyst was pre-treated in a
specially-designed quartz tube under a hydrogen atmosphere
−
1
(
99.999% purity, 30 mL min ) at 673 K for 2 h before use.
The catalyst was then immediately mixed with solvent
containing isopropanol and water in a volume ratio of 9 : 1)
x
Fig. 1 Low-angle XRD patterns of the Pt/15TS and Pt–FeO /15TS-T
catalysts.
(
This journal is © The Royal Society of Chemistry 2017
Catal. Sci. Technol.

View Article Online
Paper
Catalysis Science & Technology
Fig. 2
N
2
-physisorption isotherms and pore size distribution of Pt/
1
5TS and Pt–FeO /15TS-T catalysts.
x
was doped to the Pt/15TS catalyst, the BET specific surface
area of the Pt–FeO /15TS catalyst was in the range of 339 to
x
2
−1
3
6
49 m g . The average pore diameters were in the range of
.5–7.2 nm as evaluated by the BJH method.
From the SEM images of Fig. 3, sphere-like aggregates
larger than 500 nm were detected for pure TiO . In contrast,
2
the TiO
than that of the pure TiO
2
aggregate size in 15TS composites was much smaller
, and many well-dispersed TiO ag-
2
2
gregates smaller than 30 nm located outside the SBA-15
mesopores were clearly observed. In other words, the growth
of TiO
2
particles was greatly restrained when they were
coated onto SBA-15. At the same time, addition of Pt or FeOx
did not change its appearance and still maintained the struc-
ture of SBA-15.
The wide-angle powder XRD patterns were measured to in-
vestigate the crystalline phases of TiO
shown in Fig. 4, there are no distinct TiO
for 15TS composites, further demonstrating that mesoporous
SBA-15 can effectively suppress the growth of TiO particles,
resulting in high dispersion of TiO . Besides, the weak
2
and Pt crystallites. As
2
crystallite peaks
2
2
Pt(111) diffraction peak of the Pt/15TS catalyst indicates that
the Pt particles are well dispersed on the 15TS composites.
Nonetheless, according to the Scherrer equation, the average
Pt particle size for the Pt/15TS catalyst centers at 3.2 nm;
while for the Pt/SBA-15 and Pt/TiO
2
catalysts, it is focused at
, with a perfect ru-
5
.8 and 2.0 nm, respectively. The pure TiO
2
4
6
tile crystalline phase, can have strong interactions with
supported Pt nanoparticles and make them uniformly dis-
Fig. 3 SEM images of (a and b): SBA-15; (c and d): TiO
5TS; (g and h): Pt/15TS; (i and j): Pt–FeO /15TS-773; (k and l): used Pt–
FeO /15TS-773.
2
; (e and f):
2
persed on its surface. After coating TiO with 15 wt% loading
1
x
inside the SBA-15 mesoporous channels, only amorphous
titania was formed with a few layers so that the interaction
between the amorphous titania and Pt nanoparticles became
x
weaker than that of pure TiO with a perfect rutile crystalline
2
phase. Consequently, the size of Pt particles supported on
the Pt/15TS catalyst was smaller than that of the Pt/SBA-15
catalyst.
1
5TS composites is bigger than that supported on pure TiO
2
.
Nevertheless, due to somewhat interaction of Pt nano-
After FeO was doped to the Pt/15TS catalyst, the diffrac-
x
particles with amorphous TiO
2
, the average Pt particle size of
tion peak assigned to Pt crystallites is broader when the
Catal. Sci. Technol.
This journal is © The Royal Society of Chemistry 2017

View Article Online
Catalysis Science & Technology
Paper
−
1
Table 1 Relevant physicochemical parameters of relevant samples
of Pt active sites per second) could reach 0.41 s with the
Pt/15TS catalyst, much higher than those obtained with the
S
BET
V
p
Pore diameter
(nm)
2
−1
3
−1
Pt/TiO
0
2
−
and Pt/SBA-15 catalysts, which furnished TOFs of
.28 s and 0.18 s , respectively. In addition, the Pt/15TS
catalyst afforded slightly lower selectivity to COL by compari-
Entry
Catalyst
(m g
)
(cm g )
1
−1
1
2
3
4
SBA-15
Pt/15TS
Pt–FeO
Pt–FeO
830
345
349
339
1.10
0.73
0.80
0.77
8.1
7.2
6.5
7.2
x
/15TS-473
/15TS-773
son with the Pt/TiO
Pt/SBA-15 catalyst.
2
catalyst, but much higher than the
x
Clearly, the Pt/15TS catalyst showed superior catalytic ac-
tivity to those catalysts supported on TiO or SBA-15 alone.
2
The enhanced activity of the Pt/15TS catalyst might be caused
by the positive effect of the 15TS composites. As for the aver-
age Pt particle size for the Pt catalysts supported on different
materials, it increases in the order: Pt/TiO < Pt/15TS < Pt/
2
SBA-15, while the activity in terms of TOF values obtained
with these Pt catalysts increases in another sequence: Pt/SBA-
1
5 < Pt/TiO < Pt/15TS. Therefore, it is speculated that the Pt
2
particle size is a less influential factor; however, the interac-
tion between the Pt nanoparticles and support would influ-
ence the surface electronic properties of Pt nanoparticles and
likely cause considerable changes in their activity and selec-
tivity. The 15TS composites contained highly-dispersed TiO
2
with a thin layer coated on the SBA-15 surface and no crystal-
line phase of rutile or anatase was observed according to the
XRD results. The physicochemical properties of highly dis-
persed and amorphous TiO are quite different from those of
2
Fig. 4 Wide-angle XRD patterns of the Pt-based catalysts, where #
represents the as-calcined sample without reduction.
2
bulk TiO , so that the interaction with Pt nanoparticles will
be somewhat different resulting in different catalytic perfor-
mances for the supported Pt catalysts toward the selective
hydrogenation of CAL to COL.
catalyst precursor was calcined at 473 K before reduction, in-
dicating that Pt nanoparticles with smaller size are dominant
on the Pt–FeO /15TS-473 catalyst. However, if the catalyst pre-
x
x
3.3. Hydrogenation of CAL with the Pt–FeO /15TS catalysts
cursor was calcined at a higher temperature like 773 K, the Pt
nanoparticles aggregated to form relatively larger particles for
In order to further improve the catalytic performance of the
Pt/15TS catalysts, we attempted to modify the Pt/15TS cata-
the Pt–FeO
x
/15TS-773 catalyst. In addition, the weak diffrac-
lysts with FeO
found to be 0.25 in the literature,
15TS catalysts with the Fe/Pt molar ratio of 0.25 and investi-
gated the catalytic performance for the tested reaction. To
our delight, both the CAL conversion and COL selectivity
. Since the optimal Fe/Pt molar ratio was
x
2
4,47
tion peak assignable to TiO at a 2 theta of 25.8° is also
x
we prepared Pt–FeO /
2
4
6
detected. The dispersion of Pt particles was also character-
ized using TEM. As displayed in Fig. 5, the Pt particle size
distribution of Pt/15TS is centered at 3.0–4.0 nm, while those
for the Pt–FeO /15TS-473 and Pt–FeO /15TS-773 catalysts are
were greatly enhanced with the FeO
-promoted Pt/15TS cata-
x
x
x
focused at 2.0–3.0 nm and 4.5–5.0 nm, respectively.
lyst. Accordingly, the Pt–FeO /15TS catalyst furnished 99.0%
x
CAL conversion and 84.5% selectivity to COL under the same
conditions (Table 2) as the Pt/15TS catalyst.
3
.2. Hydrogenation of CAL with the Pt-based catalysts
According to the discussion above, compared with the Pt/
The Pt/15TS catalyst was firstly applied to the liquid-phase
x
15TS catalyst, the FeO -promoted Pt/15TS catalyst had much
hydrogenation of CAL. For comparison, the Pt/TiO and Pt/
SBA-15 catalysts were also investigated for the tested reaction.
higher catalytic ability under the same conditions and CAL
was almost fully converted. To explore the superior catalytic
2
As listed in Table 2, the Pt/TiO
2
catalyst gave about 39% CAL
x
performance of the FeO -promoted Pt/15TS catalyst to a great
conversion and 76% selectivity to COL within 1 h, while the
Pt/SBA-15 catalyst showed only 22% CAL conversion and 41%
selectivity to COL. When coating TiO with 15 wt% loading
2
onto SBA-15 to form 15TS composites for loading Pt nano-
particles, the Pt/15TS catalyst afforded greatly improved cata-
lytic performance with nearly 90% CAL conversion and a se-
lectivity to COL of 64%. The activity (represented by TOF,
defined as the number of moles of converted CAL per mole
extent, the substrate/catalyst molar ratio was increased three
times of that for the Pt/15TS catalyst and the dosage of the
catalyst was decreased to a half. Table 3 lists the reaction re-
sults obtained with the enlarged substrate/catalyst molar
ratio. Consequently, the Pt–FeO /15TS catalyst showed 41.6%
x
CAL conversion and 82.0% selectivity to COL.
By taking into account that calcination at an elevated tem-
perature may be beneficial for the metal–support interaction,
This journal is © The Royal Society of Chemistry 2017
Catal. Sci. Technol.

View Article Online
Paper
Catalysis Science & Technology
x x
Fig. 5 TEM images and particle size distributions of Pt-based catalysts: (a) Pt–FeO /15TS-473; (b) Pt–FeO /15TS-773; and (c) Pt/15TS.
the catalyst precursors were calcined in air at an elevated
temperature before reduction in sodium formate solution. To
further improved, which afforded 68.0% CAL conversion and
86.4% selectivity to COL under the same conditions, with the
TOF reaching 3.06 s , about 7.4 times higher than that with
the Pt/15TS catalyst.
Furthermore, to understand the evolution of the hydroge-
nation product, we also investigated the kinetic behaviors of
−
1
our delight, the Pt–FeO /15TS-473 catalyst showed a higher
x
conversion of CAL (58.8%), and the selectivity to COL was
slightly increased to 83.2%. With the increase of the calcina-
tion temperature for the Pt–FeO /15TS catalyst precursor, the
x
catalytic performance of the Pt–FeO
x
/15TS-773 catalyst was
x
the selective hydrogenation of CAL with the Pt–FeO /15TS-
Catal. Sci. Technol.
This journal is © The Royal Society of Chemistry 2017

View Article Online
Catalysis Science & Technology
Paper
Table 2 Hydrogenation of CAL with different Pt-based catalystsa
Average
Pt size
(nm)
Sel. (%)
COL
b
c
d
Disp.
(%)
Conv.
(%)
TOF
1
−
Entry
Catalyst
Pt/15TS
(s
)
HCAL
HCOL
1
2
3
4
3.2
2.0
5.8
3.8
35.3
56.5
19.5
29.7
90.0
39.0
22.3
99.0
0.41
0.28
0.18
1.36
64.0
75.7
40.9
84.5
18.4
17.8
46.0
4.1
17.6
6.5
13.1
11.4
Pt/TiO
Pt/SBA-15
Pt–FeO /15TS
2
x
a
b
Reaction conditions: 50 mg Pt catalyst; 7.5 mmol CAL; 4.0 MPa H
2
; 18 mL isopropyl alcohol + 2 mL water; 1200 rpm; 363 K; 1 h. Pt particle
c
d
size was calculated from the Scherrer equation. Dispersion was calculated based on dispersion (%) × d (Pt particle size in nm) = 1.13. TOF
was defined as the number of moles of converted CAL per mole of Pt active sites per second.
Table 3 Hydrogenation of CAL with different Pt–FeO
x
/15TS catalystsa
Average
Pt size
(nm)
Sel. (%)
COL
b
c
d
Dispersion
(%)
Conv.
(%)
TOF
1
−
Entry
Catalyst
(s
)
HCAL
HCOL
1
2
3
4
5
Pt–FeO
Pt–FeO
Pt–FeO
Pt–FeO
Pt–FeO
x
x
x
x
x
/15TS
/15TS-473
/15TS-773
3.8
2.9
5.2
5.2
—
29.7
38.9
21.7
21.7
—
41.6
58.8
68.0
41.2
54.6
1.36
1.47
3.06
1.85
—
82.0
83.2
86.4
68.0
84.3
15.5
12.6
9.6
24.0
11.8
2.5
4.2
3.9
8.0
3.9
e
/15TS-773f
/15TS-773
a
b
2
Reaction conditions: 25 mg catalyst; 11.25 mmol CAL; 2.0 MPa H ; 9 mL isopropyl alcohol + 1 mL water; 0.5 h; 1200 rpm; 363 K. Average Pt
c
particle size (nm) was calculated from the TEM images. Dispersion was calculated based on dispersion (%) × d (Pt particle size in nm) = 1.13.
d
f
e
TOF was defined as the number of moles of converted CAL per mole of Pt active sites per second. The reaction was conducted at 303 K.
The as-calcined Pt–FeO /15TS-773 without reduction or pre-treatment in flowing hydrogen at 673 K was applied.
x
7
73 catalyst. As revealed in Fig. 6, the conversion of CAL
tion was conducted at room temperature as well. As also
gradually increased with time and realized complete CAL
conversion within 75 min. To our delight, the selectivity to
COL of over 86% almost kept unchanged till the full conver-
sion of CAL. If the reaction time was further prolonged, the
excessive hydrogenation still proceeded, and as a result, the
selectivity to HCOL obviously increased accompanied by the
declined selectivity to COL and HCAL.
listed in Table 3, the Pt–FeO /15TS-773 catalyst afforded
x
41.2% CAL conversion with 68.0% selectivity to COL. The se-
lectivity to COL at room temperature was comparatively lower
than that obtained at 363 K, because the CC bond hydroge-
nation was thermodynamically favored, in accordance with
4
8
−1
the literature. Nevertheless, the TOF value was still 1.85 s ,
much higher than that with the Pt/15TS catalyst at 363 K.
Based on the discussion mentioned above, we got to know
that the calcination of the catalyst precursor in air at 773 K
can greatly enhance the CAL hydrogenation. Compared with
Moreover, to explore the catalytic activity of the Pt–FeO
x
/
1
5TS-773 catalyst to the greatest extent, the CAL hydrogena-
x
the Pt/15TS catalyst, the Pt–FeO /15TS catalyst improved the
activity and selectivity remarkably, mainly due to the intimate
contact of Pt entities with FeOx.
x
To fully understand the performance of the Pt–FeO /15TS
catalyst, the comparison was also made with other Pt–Fe cata-
lysts reported in the literature. For instance, the bimetallic
Pt–Fe catalyst supported on mesoporous carbon prepared by
the incipient wetness impregnation method afforded a TOF
−
1
of 0.049 s , which was calculated using the results obtained
2
8
with the 5 wt% Pt–0.8 wt% Fe/C-SA catalyst. The Pt–Fe cata-
lyst supported on the carbon nanotubes prepared by micro-
−
1
48
wave heating gave 0.94–2.21 s TOF. These TOF values are
lower than that afforded by the Pt–FeO /15TS-773 catalyst in
the present work. Moreover, for the Pt–FeO /SiO catalysts
x
x
2
prepared by a galvanic displacement method, the CAL con-
sumption rate normalized to the amount of Pt (MSACAL, de-
fined as the moles of converted CAL per gram of Pt per hour)
Fig. 6 Kinetic profiles of liquid-phase selective hydrogenation of CAL
with the Pt–FeO /15TS-773 catalyst. The reaction conditions were
identical to those for entry 3 in Table 3 except the reaction time.
−1
−1 49
was in the range of 0.89–2.24 mol gPt h , which is much
x
−
1
−1
lower than the highest MSACAL of 12.24 mol g
h
This journal is © The Royal Society of Chemistry 2017
Catal. Sci. Technol.

View Article Online
Paper
Catalysis Science & Technology
(
calculated using the same method as the Pt–FeO /SiO cata-
the first run. It can be interpreted that the catalyst surface
was reconstructed after the first run and the catalyst surface
was more suitable for the selective hydrogenation of CAL to
x
2
lysts in ref. 49) furnished by the Pt–FeO /15TS-773 catalyst in
this study. Additionally, the selectivity to COL about 86.4% is
also slightly higher than that of the Pt–FeO /SiO catalysts
(
x
4
7,50
the desired product COL.
leaching amount in the filtrate using ICP-AES and to our de-
light, the Pt–FeO /15TS-773 catalyst is stable and the amount
We also detected the Pt
x
2
84.0% selectivity at the highest MSACAL).
In addition, we also made a comparison between the Pt–
x
FeO /15TS-773 catalyst in this study and Pt catalysts
of leached Pt was below the detection limit of ICP-AES, which
further demonstrated that Pt nanoparticles were stable
enough during the recycling processes. This may be attrib-
uted to the strong interaction between Pt–FeOx and the
metal–support, which occurred when the catalyst was cal-
cined and pre-treated in a hydrogen flow at 673 K. The effect
would enhance the stability of Pt and effectively prevent
leaching of Pt during the recycling processes. Meanwhile, we
also characterized the recycled catalyst using SEM. As also
displayed in Fig. 3(k and l), the morphology of the used Pt–
x
supported on reduced graphene oxide (RGO) published in
the literature. The monometallic Pt/RGO catalyst reached the
−
1
highest TOF of 26.7 min calculated using the total amount
of Pt atoms for the selective hydrogenation of CAL with
2
3
8
5.3% selectivity to COL. We noticed that the Pt/RGO cata-
lyst had an average Pt particle size of 2 nm with a dispersion
of about 56.5%. According to our calculation method, Pt/
−
1
RGO afforded a TOF value of 0.79 s . Besides, the same
group also investigated a Pt Sn/SnO /RGO hybrid for the se-
3
2
2
9
lective hydrogenation of unsaturated aldehydes. As a result,
the hybrid with 0.6–1.2 nm Pt Sn nanoparticles furnished a
FeO /15TS-773 catalyst still maintained the perfect channel-
x
3
structure of the SBA-15 host and no TiO
on the outer surface. This confirms again that the Pt–
FeO /15TS-773 catalyst was stable enough so that it can be re-
2
particles aggregated
−
1
−1
TOF of 29.1 min (0.485 s ) for the selective hydrogenation
of CAL. Although the selectivity to COL (92.5%) with the hy-
x
brid catalyst was slightly higher than that with the Pt–FeO
x
/
covered and reused several times without obvious loss in cat-
alytic performance.
1
1
5TS-773 catalyst in the present work (86.4%), the Pt–FeOx/
5TS-773 catalyst afforded much higher activity in terms of
With regards to the declined CAL conversion after run-
ning eight cycles, there are a few possible reasons. The first
one is the gradually decreased catalyst amount. In order to
wash out the adsorbed reactant and product on the catalyst
surface, the recycled catalyst was washed with isopropyl alco-
hol and then centrifuged 3–4 times after each cycle. As a re-
sult, the total amount of the recycled catalyst decreased due
to the inevitable washing away of the catalyst with the sol-
vent, so that the amount of the catalyst subjected to the next
run was less than that for the previous cycle. We weighed
the catalyst after eight cycles and only 64% of the catalyst
was recovered after the eight cycles. The second reason
might be that the strongly-adsorbed species occupied the ac-
−
1
TOF value (3.06 s ).
3
.4. Reusability of the Pt–FeO /15TS catalyst
x
Reusability is one of the important factors to be considered
for heterogeneous catalysts involved in a liquid-phase reac-
tion. Therefore, we investigated the recyclability of the Pt–
FeO /15TS-773 catalyst toward the liquid-phase hydrogena-
x
tion of CAL. As a result, the catalyst showed no distinct loss
in activity or selectivity to COL even after eight cycles (Fig. 7).
Moreover, the CAL conversion presented a volcanic trend. We
noticed that higher CAL conversions and COL selectivities
were furnished with the used Pt–FeO
x
/15TS-773 catalyst after
x
tive sites of the Pt–FeO /15TS-773 catalyst so that the active
sites participating in adsorption and activation of the reac-
tant for the next run are actually decreased. The last possi-
ble reason is the slight aggregation of Pt particles during
the recycling process.
3
.5. Further characterization of the Pt-based catalysts
In order to study the Pt–FeOx and Pt–support interactions,
-TPR was then conducted for the as-calcined Pt–FeO /15TS-
H
2
x
7
7
73 catalyst. For comparison, the similar as-calcined Pt/15TS-
73 catalyst without addition of FeO was also prepared and
x
studied by H
73 sample, there was only one weak but obvious reduction
peak centered at around 553 K, which can be attributed to
2
-TPR. From Fig. 8, for the as-calcined Pt/15TS-
7
4
9
the reduction of PtO
x
.
x
As for the as-calcined Pt–FeO /15TS-
773 catalyst, the reduction of PtOx was shifted to a higher
temperature at 627 K, about 74 K higher than that for the as-
calcined Pt/15TS-773 catalyst. This demonstrates that the
Fig.
x
7 Reusability of the Pt–FeO /15TS-773 catalyst toward the
strong interaction of PtO with FeO exists in the as-calcined
selective hydrogenation of CAL. The reaction conditions are identical
to those for entry 3 in Table 3.
x
x
Pt–FeO /15TS-773 sample. Besides, a broad H -consumption
x
2
Catal. Sci. Technol.
This journal is © The Royal Society of Chemistry 2017

View Article Online
Catalysis Science & Technology
Paper
cies. The possible reason for the extremely low H/Pt ratio is
that most Pt precursors in the as-calcined Pt–FeO /15TS-773
x
0
catalyst already decomposed to Pt species before H
2
-TPR
measurement, which might occur during calcination in air at
73 K. To verify the Pt crystalline phase for the as-calcined
Pt–FeO /15TS-773 catalyst, the XRD pattern was measured. As
7
x
already displayed in Fig. 4, the as-calcined sample showed
distinct Pt(111) diffractions, confirming that most of the Pt
precursors have decomposed to Pt atoms during calcination
in air at 773 K.
Furthermore, we subjected the as-calcined Pt–FeO /15TS-
x
7
5
73 catalyst to the hydrogenation of CAL. As a result, it gave
4.6% CAL conversion and 84.3% selectivity to COL (Table 3).
Although the CAL conversion was lower than that obtained
with the Pt–FeO /15TS-773 catalyst under the same condi-
x
tions, the results indicate that the as-calcined Pt–FeO /15TS-
x
Fig. 8
calcined Pt–FeO
H
2
-TPR profiles for the as-calcined Pt/15TS-773 and the as-
/15TS-773 catalysts.
773 catalyst was already active and selective, verifying that
most of the Pt precursors were decomposed to Pt atoms dur-
0
x
ing calcination.
To further characterize the surface electronic properties,
peak due to the reduction of iron oxides at temperatures
x
the as-calcined Pt–FeO /15TS-773 catalyst was probed by XPS.
4
9
higher than 794 K was also detected.
Furthermore, we also calculated the H
amount of the as-calcined catalyst. Consequently, the H
take for the as-calcined Pt–FeO /15TS-773 catalyst was about
For comparison, the as-calcined Pt/15TS-773 sample was also
characterized using XPS as well. As displayed in Fig. 9A, the
XPS spectra can be deconvoluted to two Pt species for the as-
2
consumption
up-
2
calcined Pt/15TS-773 and Pt–FeO /15TS-773 catalysts, with
x
x
−
1
0
.009 mmol g . The H/Pt ratio was also calculated corre-
spondingly to be about 0.07 for the as-calcined Pt–FeO /15TS-
73 catalyst, much lower than the stoichiometric value of 4.0
the Pt 4f7/2 peaks appearing at 71.0 and 73.0 eV, respectively.
According to the literature, the Pt 4f7/2 peaks observed at
x
0
7
70.7–71.3 eV can be assigned to Pt , while the Pt4f peaks at
7
/2
0
47,49
when chloroplatinic acid was completely reduced to Pt spe-
72.4–74.6 eV could be assigned to PtO.
Therefore, the
Fig. 9 (A) Pt4f XPS spectra measured after in situ pre-treatment in flowing hydrogen at 673 K for 2 h: (a) Pt/15TS-773 and (b) Pt–FeO
and Pt4f spectra obtained with the as-calcined samples: (c) Pt–FeO /15TS-773 and (d) Pt/15TS-773. (B) Fe2p XPS spectra for the (a) as-calcined Pt–
FeO /15TS-773 and (b) Pt–FeO /15TS-773 catalysts after in situ pre-treatment in flowing hydrogen at 673 K for 2 h.
x
/15TS-773;
x
x
x
This journal is © The Royal Society of Chemistry 2017
Catal. Sci. Technol.

View Article Online
Paper
Catalysis Science & Technology
0
binding energy at 71.0 eV can be assigned to Pt species and
and Pt particles occurred when the catalysts were pre-treated
2
+
53,54
that at 73.0 eV was ascribed to Pt species. For the as-
calcined Pt/15TS-773 catalyst, the relative ratios of Pt and
Pt are 85.4% and 14.6%, respectively; while for the as-
calcined Pt–FeO /15TS-773 catalyst, the relative ratios are
9.6% and 20.4%, respectively. The XPS results further con-
firmed the conclusion of H -TPR that most of the Pt precur-
sors in the as-calcined Pt/15TS-773 or Pt–FeO /15TS-773 cata-
lysts already decomposed to Pt species. In addition, for the
under a hydrogen flow at 673 K.
take place from the Pt nanoparticles to the support.
Electron transfer might
0
46,55
In
2
+
2+
addition, the Pt–FeO /15TS-773 catalyst had more Pt and
x
4
+
Pt species on the catalyst surface, revealing that the inti-
mate contact of Pt species with FeO and thus the Pt–FeO
interaction occurred with the electron transfer from Pt to the
x
7
x
x
2
4
7–50,56
iron oxides.
x
As for the Fe2p XPS spectrum of Pt–FeO /15TS-773 after in
x
0
2
+
as-calcined Pt–FeO /15TS-773 catalyst, there are more Pt
situ pre-treatment in a hydrogen flow at 673 K, it is almost
x
species on the surface compared with the as-calcined Pt/
5TS-773 catalyst, demonstrating that there are strong inter-
actions between Pt species and FeOx species. Furthermore,
the same as that for the as-calcined Pt–FeO /15TS-773 cata-
x
1
lyst. This indicates that the Fe species did not change a lot
during reduction or pre-treatment under a hydrogen flow at
673 K.
the Fe 2p XPS spectrum for the as-calcined Pt–FeO /15TS-773
x
catalyst is also shown in Fig. 9B. The positions of the satellite
peaks for the Fe 2p peaks are very sensitive to the oxidation
states and these peaks have been used for qualitative deter-
mination of the ionic states of iron. For the as-calcined Pt–
FeO /15TS-773 catalyst, the BE for Fe 2p is at about 709.9
From the discussion mentioned above, there are intimate
and strong interactions between Pt and the 15TS support and
between Pt and FeOx. Such interactions changed the
electronic properties of Pt nanoparticles and there are pre-
δ+
2+
dominant electron-deficient Pt species with more Pt and
x
3/2
4
+
eV, with a satellite peak at 715.5 eV, which can be assigned
Pt species on the surface of the Pt–FeO
x
/15TS-773 catalyst.
2
+ 51,52
to Fe .
On recalling the experiments in the present work,
When the Pt–FeO /15TS-773 catalyst was used for the hydro-
x
3
+
δ+
we introduced FeCl with a Fe precursor into the catalyst,
genation, the Pt species are beneficial for the preferential
3
2
+
47,50
while the existence of Fe species further indicated that
more intimate and stronger Pt–FeO interactions occurred
when the catalyst precursor was calcined in air at 773 K. This
adsorption and activation of the carbonyl group.
More-
x
over, the hydrogenation at the CO bond was further en-
hanced by the intimate interactions between Pt–FeO entities
x
is in good agreement with the H
strong interaction between Pt–FeO
2
-TPR results. Due to the
, the reduction of the as-
in which the cationic Fe ions play a role for the selective acti-
2
4,47,49
x
vation of the CO bond.
x
Hence, Pt–FeO /15TS-773
calcined Pt–FeO /15TS-773 catalyst needs relatively higher
temperature when compared with that of the as-calcined Pt/
exhibited superior performance including the CAL conversion
and COL selectivity.
x
1
5TS-773 catalyst.
Moreover, in order to understand the promotion effect of
FeO in the Pt–FeO /15TS catalyst on the selective hydrogena-
x x
4. Conclusions
tion of CAL and to correlate with the reaction results, the XPS
2
TiO @SBA-15 composites were prepared via a facile sol–gel
measurement of Pt–FeO /15TS-773 after in situ pre-treatment
under a hydrogen flow at 673 K for 2 h was also evaluated by
XPS. As also displayed in Fig. 9A, the XPS spectrum can be
method and applied for loading Pt nanoparticles towards the
liquid-phase hydrogenation of cinnamaldehyde to cinnamyl
alcohol. The Pt/TiO @SBA-15 catalysts greatly enhanced the
2
x
deconvoluted to three Pt species for the Pt–FeO /15TS-773
selective hydrogenation of CAL compared with Pt catalysts
x
catalyst, with the Pt 4f7/2 peaks appearing at 71.7, 74.0 and
supported on TiO or SBA-15 alone. Furthermore, doping of
2
7
5.5 eV, respectively. Since the binding energy at 71.7 eV is
x 2
FeO to the Pt/TiO @SBA-15 catalyst together with calcination
of the catalyst precursor in air at an elevated temperature fur-
0
2+
higher than that of Pt , but lower than that of Pt , it can be
assigned to Pt species (0 < δ < 2). The binding energies at
7
respectively. The relative ratios of Pt , Pt and Pt for the
Pt–FeO /15TS-773 catalyst are 56.5%, 34.5% and 9%, respec-
δ+
ther improved the catalytic performance. As a result, a TOF
2
+
4+
−1
4.0 and 75.5 eV could be ascribed to Pt and Pt species,
value of 3.06 s was furnished by the Pt–FeO
x 2
/TiO @SBA-15-
δ+
2+
4+
773 catalyst, about 7.4 times higher than that with the Pt/
x
TiO @SBA-15 catalyst. It is noteworthy that 86.4% selectivity
2
tively. For comparison, the Pt/15TS-773 catalyst was also
probed by XPS after in situ pre-treatment in flowing hydrogen
at 673 K for 2 h and the XPS spectrum can be deconvoluted
to two species as a result, with the Pt 4f7/2 peaks appearing at
x 2
to COL can be furnished over the Pt–FeO /TiO @SBA-15-773
catalyst. The most remarkable feature of the Pt–FeOx/
TiO @SBA-15-773 catalyst is that it could be recycled at least
2
eight times without distinct loss in activity or selectivity to
COL. By combination of the spectroscopic and temperature-
programmed characterization techniques, it was proved that
7
1.7 and 74.0 eV. Similarly, the Pt/15TS-773 catalyst surface
δ+
2+
contained 71.8% Pt and 28.2% Pt species.
Compared with the Pt 4f7/2 peak of the as-calcined Pt/
2
there are strong interactions between Pt and TiO @SBA-15
0
1
5TS-773 and Pt–FeO /15TS-773 catalysts, of which Pt atoms
composites and also between Pt–FeO , resulting in that the
x
x
δ+
are dominant on the surface with a Pt 4f7/2 peak at 71.0 eV,
there is a 0.7 eV shift to higher BEs for the reduced and pre-
treated samples. The shift in the Pt 4f7/2 peak clearly demon-
strated that strong interactions between the 15TS support
electron-deficient Pt species are dominant on the catalyst
surface. The electron-deficient Pt species, together with Fe
species, in the Pt–FeO /TiO @SBA-15-773 catalyst are helpful
δ+
2+
x
2
for the preferential adsorption and activation of the carbonyl
Catal. Sci. Technol.
This journal is © The Royal Society of Chemistry 2017

View Article Online
Catalysis Science & Technology
Paper
group, thus furnishing greatly improved catalytic perfor-
mance towards the selective hydrogenation of CAL to COL.
19 E. Castillejos, M. Jahjah, I. Favier, A. Orejón, C. Pradel, E.
Teuma, A. M. Madseu Bulto, P. Serp and M. Gomez,
ChemCatChem, 2012, 4, 118–122.
2
2
2
2
2
2
2
2
2
0 P. D. Zgolicz, J. P. Stassi, M. J. Yanez, O. A. Scelza and S. R.
Conflicts of interest
de Miguel, J. Catal., 2012, 290, 37–54.
1 M. Niu, Y. Wang, L. I. Wenjiang, J. Jiang and Z. Jin, Chin. J.
Catal., 2013, 34, 674–678.
2 K. R. Kahsar, S. Johnson, D. K. Schwartz and J. W. Medlin,
Top. Catal., 2014, 57, 1505–1511.
3 J. Shi, R. Nie, P. Chen and Z. Hou, Catal. Commun., 2013, 41,
There are no conflicts of interest to declare.
Acknowledgements
This work was supported by the National Natural Science
Foundation of China (21273076 and 21373089), the Open Re-
search Fund of Top Key Discipline of Chemistry in Zhejiang
Provincial Colleges and Key Laboratory of the Ministry of Edu-
cation for Catalysis Materials (Zhejiang Normal University)
1
01–105.
4 P. Gallezot and D. Richard, Catal. Rev.: Sci. Eng., 1998, 40,
1–126.
8
5 A. Siani, O. S. Alexeev, G. Lafaye and M. D. Amiridis,
J. Catal., 2009, 266, 26–38.
6 Y. Li, P. F. Zhu and R. X. Zhou, Appl. Surf. Sci., 2008, 254,
(ZJHX2013), and the Shanghai Leading Academic Discipline
Project (B409).
2
609–2614.
7 Z. Guo, Y. Chen, L. Li, X. Wang, G. L. Haller and Y. Yang,
J. Catal., 2010, 314, 276–326.
8 N. Mahata, F. Gonçalves, M. F. R. Pereira and J. L.
Figueiredo, Appl. Catal., A, 2008, 339, 159–168.
References
1
2
3
J. P. Stassi, P. D. Zgolicz, S. R. de Miguel and O. A. Scelza,
J. Catal., 2013, 306, 11–29.
J. Teddy, A. Falqui, A. Corrias, D. Carta, P. Lecante, I. Gerber
and P. Serp, J. Catal., 2011, 278, 59–70.
Y. Yuan, S. Yao, M. Wang, S. Lou and N. Yan, Curr. Org.
Chem., 2013, 17, 400–413.
29 J. Shi, M. Zhang, W. Du, W. Ning and Z. Hou, Catal. Sci.
Technol., 2015, 5, 3108–3122.
30 P. Kluson and L. Cerveny, Appl. Catal., A, 1995, 128, 13–31.
31 S. J. Tauster and S. C. Fung, J. Catal., 1978, 55, 29–35.
32 T. Ekou, L. Ekou, A. Vicente, G. Lafaye and S. Pronier, J. Mol.
Catal. A: Chem., 2011, 337, 82–88.
33 P. Claus, S. Schimpf, R. Schodel, P. Kraak, W. Morke and D.
Honicke, Appl. Catal., A, 1997, 165, 429–441.
34 M. Bidaoui, C. Especel, N. Bouchenafa-Saib, D. Duprez and
O. Mohammedi, Appl. Catal., A, 2012, 445, 14–25.
35 M. Abid, V. Paul-Boncour and R. Touroude, Appl. Catal., A,
2006, 297, 48–59.
36 A. Dandekar and M. A. Vannice, J. Catal., 1999, 183, 344–354.
37 S. A. D. S. Corradini, G. G. Lenzi, M. K. Lenzi, C. M. F.
Soares and O. A. A. Santos, J. Non-Cryst. Solids, 2008, 354,
4865–4870.
4
5
S. Bhogeswararao and D. Srinivas, J. Catal., 2012, 285, 31–40.
B. H. Zhao, J. G. Chen, X. Liu, Z. W. Liu, Z. Hao, J. Xiao and
Z. T. Liu, Ind. Eng. Chem. Res., 2012, 51, 11112–11121.
X. Chen, H. Li, W. Dai, J. Wang, Y. Ran and M. Qiao, Appl.
Catal., A, 2003, 253, 359–369.
6
7
8
9
Z. Tian, Q. Li, Y. Li and S. Ai, Catal. Commun., 2015, 61,
9
7–101.
D. Loffreda, F. Delbecq, F. Vigné and P. Sautet, J. Am. Chem.
Soc., 2006, 128, 1316–1323.
C. Vriamont, T. Haynes, E. Mccague-Murphy, F. Pennetreau
and S. Hermans, J. Catal., 2015, 329, 389–400.
1
1
1
1
1
1
1
0 X. Yang, D. Chen, S. Liao, H. Song, Y. Li, Z. Fu and Y. Su,
J. Catal., 2012, 291, 36–43.
1 K. Q. Sun, Y. C. Hong, G. R. Zhang and B. Q. Xu, ACS Catal.,
38 J. S. Ratliff, S. A. Tenney, X. Hu, S. F. Conner, S. Ma and
D. A. Chen, Langmuir, 2009, 25, 216–225.
39 T. Ekou, C. Especel and S. Royer, Catal. Today, 2011, 173,
44–52.
40 P. Cheng, M. Zheng, Y. Jin, Q. Huang and M. Gu, Mater.
Lett., 2003, 57, 2989–2994.
41 H. Chun, Y. Wang and H. Tang, Appl. Catal., B, 2001, 30,
277–285.
42 L. A. Cano, M. V. Cagnoli, N. A. Fellenz, J. F. Bengoa, N. G.
Gallegos, A. M. Alvarez and S. G. Marchetti, Appl. Catal., A,
2010, 379, 105–110.
43 Y. Tang, S. Miao, B. H. Shanks and X. Zheng, Appl. Catal., A,
2010, 375, 310–317.
2
014, 1, 1336–1346.
2 A. K. Prashar, S. Mayadevi and R. Nandini Devi, Catal.
Commun., 2012, 28, 42–46.
3 K. R. Kahsar, D. K. Schwartz and J. W. Medlin, J. Am. Chem.
Soc., 2014, 136, 520–526.
4 S. Handjani, E. Marceau, J. Blanchard, J. M. Krafft and M.
Che, J. Catal., 2011, 282, 228–236.
5 W. Lin, H. Cheng, L. He, Y. Yu and F. Zhao, J. Catal.,
2
013, 303, 110–116.
6 Q. Yu, X. Zhang, B. Li, J. Lu, G. Hu, A. Jia, C. Luo, Q. Hong,
Y. Song and M. Luo, J. Mol. Catal. A: Chem., 2014, 392,
44 X. Li, W. Zheng, H. Pan, Y. Yu, L. Chen and P. Wu, J. Catal.,
2013, 300, 9–19.
45 D. Zhao, J. Feng, Q. Huo, N. Melosh, G. H. Fredrickson, B. F.
Chmelka and G. D. Stucky, Science, 1998, 279, 548–552.
46 Q. Wu, C. Zhang, B. Zhang, X. Li, Z. Ying and F. Zhao,
J. Colloid Interface Sci., 2016, 463, 75–82.
8
9–96.
7 M. Chatterjee, Y. Ikushima and F. Zhao, New J. Chem.,
003, 27, 510–513.
1
1
2
8 C. Li, Z. Shao, M. Pang, C. T. Williams, X. Zhang and C.
Liang, Ind. Eng. Chem. Res., 2012, 51, 4934–4941.
This journal is © The Royal Society of Chemistry 2017
Catal. Sci. Technol.

View Article Online
Paper
Catalysis Science & Technology
4
4
4
5
5
7 H. Pan, J. Li, J. Lu, G. Wang, W. Xie, P. Wu and X. Li,
J. Catal., 2017, 354, 24–36.
8 Z. Guo, C. Zhou, D. Shi, Y. Wang, X. Jia and J. Chang, Appl.
Catal., A, 2012, 435, 131–140.
9 Y. S. Shi, Z. F. Yuan, Q. Wei, K. Q. Sun and B. Q. Xu, Catal.
Sci. Technol., 2016, 6, 7033–7037.
0 R. Yao, J. Li, P. Wu and X. Li, RSC Adv., 2016, 6,
52 T. Yamashita and P. Hayes, Appl. Surf. Sci., 2008, 254,
2441–2449.
53 A. Lewera, L. Timperman, A. Roguska and N. Alonso-Vante,
J. Phys. Chem. C, 2011, 115, 20153–20159.
54 X. Y. Liu, A. Wang, T. Zhang and C. Y. Mou, Nano Today,
2013, 8, 403–416.
55 M. S. Kim, S. H. Chung, C. J. Yoo, M. S. Lee, I. H. Cho, D. W.
Lee and K. Y. Lee, Appl. Catal., B, 2013, 142, 354–361.
56 M. Li, X. Chen, J. Guan, X. Wang, J. Wang, C. T. Williams
and C. Liang, J. Mater. Chem., 2011, 22, 609–616.
8
1211–81218.
1 P. C. J. Graat and M. A. J. Somers, Appl. Surf. Sci., 1996, 100,
6–40.
3
Catal. Sci. Technol.
This journal is © The Royal Society of Chemistry 2017